This invention relates to a system for secondary oil recovery from an oil well. For some time, additional oil has been recovered from an oil well by introducing steam into the oil bearing formation. The usual practice is to provide a large oil fired steam oiler at a central location in an oil field and run steam through pipes along the ground to the various wells in the field. This type of system requires a substantial investment in the boiler and piping and hence is not economically satisfactory for small fields with widely spaced wells or individual wells. Also, the boilers normally burn some form of refined fuel oil rather than crude, which fuel oil must be transported to the boiler site.
An alternative configuration is suggested in U.S. Pat. No. 3,420,301 with an electrically energized heater positioned in the well casing near the oil bearing formation. The heater incorporates concentric electrodes with a space therebetween for fluid flow, and a central passage through the inner electrode for the sucker rod. This arrangement has not proved satisfactory because of the problems of placing the heater down in the well and the problems on recovering the heater when it malfunctions or for maintenance.
It is an object of the present invention to provide a new and improved system for secondary oil recovery which overcomes these disadvantages. A further object is to provide a small self contained system suitable for positioning and operation at the surface and for utilization with a single well. It is a particular object to provide such a system which may be easily and continuously monitored during operation and one which is readily accessbile for adjustment during operation and for maintenance. Another object is to provide a system which does not produce any air pollutants and which does not require any special permit for its operation.
Other objects, advantages, features and results will more fully appear in the course of the following description.